Despite the considerable health benefits of breastfeeding, initiation and duration rates continue to fall short of international guidelines. Acute mastitis is one of the main reasons why women stop breastfeeding. While antibiotics are frequently prescribed for this painful breast condition, their safety during lactation is a concern, as is the problem of antibiotic resistance.
A need for alternative therapies has led researchers to explore the potential of probiotics.
Mastitis, in brief
Mastitis is an inflammation of breast tissue that often involves an infection. Breast symptoms may include pain, redness, a lump, swelling, or being hot to the touch. Systemic symptoms include flu-like symptoms (e.g., fever, chills, aching, and/or headache). A meta-analysis of incidence found a substantial burden of mastitis—with potentially about one in four women breastfeeding up to 25 weeks postpartum affected.
Common risk factors:
- Blocked milk duct: If a breast doesn’t completely empty during feedings, milk can back up which can lead to infection.
- Cracked nipples: Bacteria from the skin’s surface and baby’s mouth can enter the milk ducts.
- Maternal fatigue: Decreased immunity and a lowered resistance to infection.
Other risk factors include having a history of mastitis, using an antifungal nipple cream, and, though disputed, using a manual breast pump.
Management of mastitis largely focuses on symptom management (hot/cold compresses, pain relievers); education on technique (including fully emptying the affected breast, feeding more frequently, and changing feeding positions often); and antibiotic therapy. Some limited evidence on the use of antibiotics in treating symptoms showed a trend towards the benefit of treatment. However, in another review of three trials of 429 women, no significant differences in the incidence of mastitis between the use of antibiotics and no antibiotics were found.
The underlying pathogenesis of mastitis is important when considering management options. The main agents of infection, Staphylococcus aureus and Streptococcus epidermidis, usually display resistance to antibiotic therapies and subsequent return of disease. Safe and effective alternatives to antibiotics are needed.
Rationale for Probiotics in Mastitis Therapy
Bacteria commonly isolated from the breast milk of healthy women include staphylococci, streptococci, micrococci, lactobacilli, and enterococci.
As stated before, acute mastitis usually has an infectious origin involving Staphylococcus aureus or Streptococcus epidermidis. When the population of potential pathogens increases at the expense of the normal mammary microbiota, mammary bacterial dysbiosis ensues, potentially leading to mastitis.
In contrast, lactobacilli may support the mammary immune systems, in part by bolstering barriers to infection by pathogens. Thus, breast milk of healthy women may be a source of potentially probiotic lactobacilli with a role in protecting mothers and/or infants against infectious diseases.
The dairy industry has long contended with mastitis in animals, with extensive study allotted to finding remedies, where also the intestine and its resident microbiota play a role. A compromised intestinal barrier may lead to leakage of lipopolysaccharides (LPS) into the blood stream which also contributes to an inflammatory response in the mammary gland. However, research has shown that short-chain fatty acids, which are produced by the gut microbiota as fermentation products, have a protective effect on mammary gland inflammatory responses and help maintain the function of the blood-milk barrier.
Probiotic Use in Mastitis
A 2021 review reported that administration of a Lactobacillus probiotic to nursing women affected by mastitis was associated with significant reductions in breastmilk Staphylococcal loads.
A systematic review and meta-analysis that included six randomized controlled trials including 1197 participants showed that oral probiotics during pregnancy can reduce the incidence of mastitis. After oral administration of probiotics, the counts of bacteria in the milk of healthy people and mastitis patients were both significantly reduced.
Examples of a few of these studies:
- Research using a combination of two breast milk-isolated strains of Ligilactobacillus salivarius and Lactobacillus gasseri appeared to be an effective therapy in women with infectious mastitis.
- In a study on 352 women with infectious mastitis, the groups receiving probiotics (Limosilactobacillus fermentum or L. salivarius) improved more and had a lower recurrence of mastitis than those assigned to the antibiotic group.
- Another study observed that L. fermentum reduced the Staphylococcus load in the breast milk of lactating mothers suffering from breast pain. Three different doses tested induced similar effects.
Researchers also looked at whether probiotics could prevent mastitis.
- When orally administered during late pregnancy to women who had experienced infectious mastitis after previous pregnancies, Ligilactobacillus salivarius prevented infectious mastitis in significantly more women than in a control group.
- And in a study of 328 women, L. salivarius intervention started from the 35th week of pregnancy until week 12 post-partum reported that those in the probiotic group were 58% less likely to experience mastitis than the placebo group.
Evidence suggests that probiotics may provide an effective measure and alternative to antibiotics in the management of lactational mastitis. Further evaluation is warranted.
Image by Valéria Rodrigues Valéria
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